Reframing the climate change challenge in light of post-2000 emission trends

The 2007 Bali conference heard repeated calls for reductions in global greenhouse gas emissions of 50 per cent by 2050 to avoid exceeding the 2 degrees C threshold. While such endpoint targets dominate the policy agenda, they do not, in isolation, have a scientific basis and are likely to lead to dangerously misguided policies. To be scientifically credible, policy must be informed by an understanding of cumulative emissions and associated emission pathways. This analysis considers the implications of the 2 degrees C threshold and a range of post-peak emission reduction rates for global emission pathways and cumulative emission budgets. The paper examines whether empirical estimates of greenhouse gas emissions between 2000 and 2008, a period typically modelled within scenario studies, combined with short-term extrapolations of current emissions trends, significantly constrains the 2000-2100 emission pathways. The paper concludes that it is increasingly unlikely any global agreement will deliver the radical reversal in emission trends required for stabilization at 450 ppmv carbon dioxide equivalent (CO2e). Similarly, the current framing of climate change cannot be reconciled with the rates of mitigation necessary to stabilize at 550 ppmv CO2e and even an optimistic interpretation suggests stabilization much below 650 ppmv CO2e is improbable.     

Cumulative carbon as a policy framework for achieving climate stabilization

The primary objective of the United Nations Framework Convention on Climate Change is to stabilize greenhouse gas concentrations at a level that will avoid dangerous climate impacts. However, greenhouse gas concentration stabilization is an awkward framework within which to assess dangerous climate change on account of the significant lag between a given concentration level and the eventual equilibrium temperature change. By contrast, recent research has shown that global temperature change can be well described by a given cumulative carbon emissions budget. Here, we propose that cumulative carbon emissions represent an alternative framework that is applicable both as a tool for climate mitigation as well as for the assessment of potential climate impacts. We show first that both atmospheric CO(2) concentration at a given year and the associated temperature change are generally associated with a unique cumulative carbon emissions budget that is largely independent of the emissions scenario. The rate of global temperature change can therefore be related to first order to the rate of increase of cumulative carbon emissions. However, transient warming over the next century will also be strongly affected by emissions of shorter lived forcing agents such as aerosols and methane. Non-CO(2) emissions therefore contribute to uncertainty in the cumulative carbon budget associated with near-term temperature targets, and may suggest the need for a mitigation approach that considers separately short- and long-lived gas emissions. By contrast, long-term temperature change remains primarily associated with total cumulative carbon emissions owing to the much longer atmospheric residence time of CO(2) relative to other major climate forcing agents.     

Economic value of improved quantification in global sources and sinks of carbon dioxide

On average, about 45 per cent of global annual anthropogenic carbon dioxide (CO(2)) emissions remain in the atmosphere, while the remainder are taken up by carbon reservoirs on land and in the oceans-the CO(2) 'sinks'. As sink size and dynamics are highly variable in space and time, cross-verification of reported anthropogenic CO(2) emissions with atmospheric CO(2) measurements is challenging. Highly variable CO(2) sinks also limit the capability to detect anomolous changes in natural carbon reservoirs. This paper argues that significant uncertainty reduction in annual estimates of the global carbon balance could be achieved rapidly through coordinated up-scaling of existing methods, and that this uncertainty reduction would provide incentive for accurate reporting of CO(2) emissions at the country level. We estimate that if 5 per cent of global CO(2) emissions go unreported and undetected, the associated marginal economic impacts could reach approximately US$20 billion each year by 2050. The net present day value of these impacts aggregated until 2200, and discounted back to the present would have a mean value exceeding US$10 trillion. The costs of potential impacts of unreported emissions far outweigh the costs of enhancement of measurement infrastructure to reduce uncertainty in the global carbon balance.     

Interactions between reducing CO2 emissions, CO2 removal and solar radiation management

We use a simple carbon cycle-climate model to investigate the interactions between a selection of idealized scenarios of mitigated carbon dioxide emissions, carbon dioxide removal (CDR) and solar radiation management (SRM). Two CO(2) emissions trajectories differ by a 15-year delay in the start of mitigation activity. SRM is modelled as a reduction in incoming solar radiation that fully compensates the radiative forcing due to changes in atmospheric CO(2) concentration. Two CDR scenarios remove 300 PgC by afforestation (added to vegetation and soil) or 1000 PgC by bioenergy with carbon capture and storage (removed from system). Our results show that delaying the start of mitigation activity could be very costly in terms of the CDR activity needed later to limit atmospheric CO(2) concentration (and corresponding global warming) to a given level. Avoiding a 15-year delay in the start of mitigation activity is more effective at reducing atmospheric CO(2) concentrations than all but the maximum type of CDR interventions. The effects of applying SRM and CDR together are additive, and this shows most clearly for atmospheric CO(2) concentration. SRM causes a significant reduction in atmospheric CO(2) concentration due to increased carbon storage by the terrestrial biosphere, especially soils. However, SRM has to be maintained for many centuries to avoid rapid increases in temperature and corresponding increases in atmospheric CO(2) concentration due to loss of carbon from the land.     

Beyond 'dangerous' climate change: emission scenarios for a new world

The Copenhagen Accord reiterates the international community's commitment to 'hold the increase in global temperature below 2 degrees Celsius'. Yet its preferred focus on global emission peak dates and longer-term reduction targets, without recourse to cumulative emission budgets, belies seriously the scale and scope of mitigation necessary to meet such a commitment. Moreover, the pivotal importance of emissions from non-Annex 1 nations in shaping available space for Annex 1 emission pathways received, and continues to receive, little attention. Building on previous studies, this paper uses a cumulative emissions framing, broken down to Annex 1 and non-Annex 1 nations, to understand the implications of rapid emission growth in nations such as China and India, for mitigation rates elsewhere. The analysis suggests that despite high-level statements to the contrary, there is now little to no chance of maintaining the global mean surface temperature at or below 2°C. Moreover, the impacts associated with 2°C have been revised upwards, sufficiently so that 2°C now more appropriately represents the threshold between 'dangerous' and 'extremely dangerous' climate change. Ultimately, the science of climate change allied with the emission scenarios for Annex 1 and non-Annex 1 nations suggests a radically different framing of the mitigation and adaptation challenge from that accompanying many other analyses, particularly those directly informing policy.     

Performance evaluation of vehicles emissions prediction models

Road traffic is a dominant source of urban air pollution. Therefore, it is necessary to quantify emission levels as accurately as possible to evaluate their impacts on the public health and the environment. Several models were developed to predict these emissions. These models can be grouped into three categories, namely, emission factors models, average speed models, and modal models. The prediction capability of most developed models is relatively poor. Therefore, there is a pressing need to improve the predictability of the existing models or to develop new ones with better accuracy. The main focus of this paper is to review different traffic emissions modeling efforts and to describe the effect of different factors on emission levels and modeling accuracy, so as to get reliable emission estimates. In addition, different models were evaluated for the prediction capability of certain emissions such as carbon monoxide (CO), nitrogen monoxide (NO), nitrogen dioxide (NO₂) and hydrocarbons (HC). These models are mainly based on traffic volume, composition, and flow. The predicted values by one of the models were compared to measured values based on field surveys. The result of comparison indicated that there is a significant difference between the measured and predicted values. These differences ranged from 17% for NO₂ to 72% in the case of CO, which suggests that the NO₂ model has better predictability. This deviation in prediction may be attributed to the fact that prediction models ignored some of the parameters affecting vehicle emissions such as the type of fuel used, air–fuel ratio, engine compression ratio, spark timing, surrounding environment, wind effect, regional characteristics and high pollutants emitters effect.     

Ocean acidification in a geoengineering context

Fundamental changes to marine chemistry are occurring because of increasing carbon dioxide (CO(2)) in the atmosphere. Ocean acidity (H(+) concentration) and bicarbonate ion concentrations are increasing, whereas carbonate ion concentrations are decreasing. There has already been an average pH decrease of 0.1 in the upper ocean, and continued unconstrained carbon emissions would further reduce average upper ocean pH by approximately 0.3 by 2100. Laboratory experiments, observations and projections indicate that such ocean acidification may have ecological and biogeochemical impacts that last for many thousands of years. The future magnitude of such effects will be very closely linked to atmospheric CO(2); they will, therefore, depend on the success of emission reduction, and could also be constrained by geoengineering based on most carbon dioxide removal (CDR) techniques. However, some ocean-based CDR approaches would (if deployed on a climatically significant scale) re-locate acidification from the upper ocean to the seafloor or elsewhere in the ocean interior. If solar radiation management were to be the main policy response to counteract global warming, ocean acidification would continue to be driven by increases in atmospheric CO(2), although with additional temperature-related effects on CO(2) and CaCO(3) solubility and terrestrial carbon sequestration.     

Emergent dynamics of the climate-economy system in the Anthropocene

Global CO(2) emissions are understood to be the largest contributor to anthropogenic climate change, and have, to date, been highly correlated with economic output. However, there is likely to be a negative feedback between climate change and human wealth: economic growth is typically associated with an increase in CO(2) emissions and global warming, but the resulting climate change may lead to damages that suppress economic growth. This climate-economy feedback is assumed to be weak in standard climate change assessments. When the feedback is incorporated in a transparently simple model it reveals possible emergent behaviour in the coupled climate-economy system. Formulae are derived for the critical rates of growth of global CO(2) emissions that cause damped or long-term boom-bust oscillations in human wealth, thereby preventing a soft landing of the climate-economy system. On the basis of this model, historical rates of economic growth and decarbonization appear to put the climate-economy system in a potentially damaging oscillatory regime.     

Changes in the use and management of forests for abating carbon emissions: issues and challenges under the Kyoto Protocol

The global carbon cycle is significantly influenced by changes in the use and management of forests and agriculture. Humans have the potential through changes in land use and management to alter the magnitude of forest-carbon stocks and the direction of forest-carbon fluxes. However, controversy over the use of biological means to absorb or reduce emissions of CO(2) (often referred to as carbon 'sinks') has arisen in the context of the Kyoto Protocol. The controversy is based primarily on two arguments: sinks may allow developed nations to delay or avoid actions to reduce fossil fuel emissions, and the technical and operational difficulties are too threatening to the successful implementation of land use and forestry projects for providing carbon offsets. Here we discuss the importance of including carbon sinks in efforts to address global warming and the consequent additional social, environmental and economic benefits to host countries. Activities in tropical forest lands provide the lowest cost methods both of reducing emissions and reducing atmospheric concentrations of greenhouse gases. We conclude that the various objections raised as to the inclusion of carbon sinks to ameliorate climate change can be addressed by existing techniques and technology. Carbon sinks provide a practical available method of achieving meaningful reductions in atmospheric concentrations of carbon dioxide while at the same time contribute to national sustainable development goals.     

Application of sensitivity analysis to oil refinery emissions

Catalyst emissions from fluidising catalytic cracking units have the potential to impact significantly on the environmental compliance of oil refineries. Traditionally it has been assumed that gas velocity and fine particles significantly impact on emission levels. Through the use of a simple fluidised bed model, sensitivity analysis was conducted to identify the key operating parameters that influence emission rates. It was found that in addition to velocity, density and mid sized particles are the most influential factors for emission rates. Further work is needed to identify how these parameters can be altered during normal operations to reduce catalyst emissions.     

Impact of including land-use change emissions from biofuels on meeting GHG emissions reduction targets: the example of Ireland

The greenhouse gases (GHG) emissions from land-use change are of particular concern for land-based biofuels. Emissions avoided by substituting fossil fuels with biofuels may be offset by emissions from direct and indirect land-use changes (LUC). There is an urgent need to investigate what impact land-use change emissions may have on the expansion of bioenergy and biofuels, in the context of EU mitigation policies. This paper focuses on Ireland, which faces a number of challenges in delivering its renewable energy and GHG reduction targets. The Irish TIMES energy systems model was used to assess the impact of a range of land-use change emissions’ levels on the evolution of Ireland’s low-carbon energy system. A reference scenario was developed where LUC is ignored and Ireland achieves a least-cost low-carbon energy system by 2050. If high indirect land-use change (ILUC) emissions are included, this results in a decrease by 30 % in bioenergy and a 68 % increase in marginal abatement costs by 2050. Hydrogen is used instead of bioenergy in the freight sector in this scenario, while private cars are fuelled by renewable electricity. If GHG emissions from ILUC were considered less severe, indigenous grass biomethane becomes the key biofuel representing 31 % of total bioenergy consumption. This is in line with recent research in Ireland of the key role that grass biomethane can play.     

Cement and carbon emissions

Because of its low cost, its ease of use and relative robustness to misuse, its versatility, and its local availability, concrete is by far the most widely used building material in the world today. Intrinsically, concrete has a very low energy and carbon footprint compared to most other materials. However, the volume of Portland cement required for concrete construction makes the cement industry a large emitter of CO₂. The International Energy Agency recently proposed a global CO₂ reduction plan. This plan has three main elements: long term CO₂ targets, a sectorial approach based on the lowest cost to society, and technology roadmaps that demonstrate the means to achieve the CO₂ reductions. For the cement industry, this plan calls for a reduction in CO₂ emissions from 2 Gt in 2007 to 1.55 Gt in 2050, while over the same period cement production is projected to increase by about 50 %. The authors of the cement industry roadmap point out that the extrapolation of existing technologies (fuel efficiency, alternative fuels and biomass, and clinker substitution) will only take us half the way towards these goals. According to the roadmap, the industry will have to rely on costly and unproven carbon capture and storage technologies for the other half of the required reduction. This will result in significant additional costs for society. Most of the CO₂ footprint of cement is due to the decarbonation of limestone during the clinkering process. Designing new clinkers that require less limestone is one means to significantly reduce the CO₂ footprint of cement and concrete. A new class of clinkers described in this paper can reduce CO₂ emissions by 20 to 30 % when compared to the manufacture of traditional PC Clinker.     

Asymmetric inter-linkages between green technology innovation and consumption-based carbon emissions in BRICS countries using quantile-on-quantile framework

The role of reliable Carbon emission measures and relevant climate policy is imperative in realizing Sustainable Development Goals. A large extent of the literature concludes the emissions-mitigating effect of green innovations in a linear framework and ignored structural changes, technological revolutions, and socio-economic reforms that create non-linearity. Apart from that, there is a murky relationship between emissions and green innovation, where two-way links exist between both variables. Therefore, this study draws the inter-linkages between green technology innovation (GI) and carbon emissions (consumption-based and terrestrial emissions) in BRICS countries using monthly data from 1990 to 2017. Our preliminary findings strictly reject the preposition of data normality and highlight that the observed relationship is quantile-dependent. Therefore, a complete set of non-linear modeling is employed that included; Quantile unit root, Quantile cointegration, Quantile causality, and Quantile on Quantile regression to unveil hidden unit root, cointegration, causality, and association between variables. The results exhibit that the emissions-mitigating effect of GI is only pronounced at higher emissions quantiles in Brazil, China, India, and Russia, whereas at lower emissions quantile, GI is weekly or positively linked with carbon emissions. On the flipside, higher carbon emissions instigate GI across medium to higher emissions quantiles in Brazil, China, and India. Unlike them, Russia produces different outcomes, where higher emissions are associated with lower GI across all quantiles. The overall results suggest that GI (carbon emissions) mitigate (instigate) carbon emissions (GI) when a country is embodied with higher level of emissions.     

Coping with carbon: a near-term strategy to limit carbon dioxide emissions from power stations

Burning coal to generate electricity is one of the key sources of atmospheric carbon dioxide emissions; so, targeting coal-fired power plants offers one of the easiest ways of reducing global carbon emissions. Given that the world's largest economies all rely heavily on coal for electricity production, eliminating coal combustion is not an option. Indeed, coal consumption is likely to increase over the next 20-30 years. However, the introduction of more efficient steam cycles will improve the emission performance of these plants over the short term. To achieve a reduction in carbon emissions from coal-fired plant, however, it will be necessary to develop and introduce carbon capture and sequestration technologies. Given adequate investment, these technologies should be capable of commercial development by ca 2020.     

Mobilising the potential towards low-carbon emissions society in Asia

Emission of CO₂, CH₄, and NO _x is among the main sources of greenhouse gases (GHGs) emitted through human activities such as fossil fuels combustion for power, heat and transportation, industrial processes, and land-use change. Low-carbon emission has become synonymous with GHG emission, which is often expressed in t CO₂ eq. as derived from the major GHG. However, CO₂ emission from fossil fuel constitutes just about 2/3 of GHGs. Low-carbon emission has received high publicity in recent years as a major reason for the potential mitigation of climate change. Achieving low GHG emission targets while decoupling the economic growth from high emissions, pollution, and resource use is desirable. This paper reviews the low-carbon emissions initiatives to develop resilient growth strategies to reduce GHG emissions in Asia and beyond. Four major initiatives, including the modelling of GHG emission and mitigation initiative; sustainable energy systems; sustainable waste management; and education and community outreach, are reviewed for mobilising the potential towards low-carbon emissions societies in Asia. Cooperation from major stakeholders, e.g. government, policy makers, financial institutions, private investors, industrial, commercial sector, residential, has been needed towards realising the goal.     

Comparing the climate effect of emissions of short- and long-lived climate agents

Multi-gas climate agreements require a metric by which emissions of gases with different lifetimes and radiative properties can be placed on a common scale. The Kyoto Protocol to the United Nations Framework Convention on Climate Change uses the global warming potential (GWP) as such a metric. The GWP has attracted particular criticism as being inappropriate in the context of climate policy which seeks to restrict warming below a given target, because it gives equal weight to emissions irrespective of the target and the proximity to the target. The use of an alternative metric, the time-dependent global temperature change potential (GTP), is examined for its suitability and the prospects for it including very short-lived species. It retains the transparency and relative ease of use, which are attractive features of the GWP, but explicitly includes a dependence on the target of climate policy. The weighting of emissions using the GTP is found to be significantly dependent on the scenarios of future emissions and the sensitivity of the climate system. This may indicate that the use of any GTP-based weighting in future policymaking would necessitate regular revisions, as the global-mean temperature moves towards a specified target.     

Decomposition and decoupling analysis of electricity consumption carbon emissions in China

Electricity consumption is one of the major contributors to greenhouse gas emissions. In this study, we build a power consumption carbon emission measurement model based on the operating margin factor. We use the decomposition and decoupling technology of logarithmic mean Divisia index method to quantify six effects (i.e., emission intensity, power generation structure, consumption electricity intensity, economic scale, population structure, and population scale) and comprehensively reflect the degree of dependence of electricity consumption carbon emissions on China’s economic development and population changes. Moreover, we utilize the decoupling model to analyze the decoupling state between carbon emissions and economic growth and identify corresponding energy efficiency policies. The results of this study provide a new perspective to understand carbon emission reduction potentials in the electricity use of China.     

基于Herriott吸收池的固定源二氧化碳浓度测量研究

准确的碳排放计量是实现“碳峰化、碳中和”目标的重要一步。在所有碳排放源中,固定排放源排放的CO2是温室效应的主要因素。因此,精确测量固定排放源CO2的浓度尤为重要。基于近红外分子吸收光谱原理并结合多次反射直接吸收光谱技术,利用35% CO2/N;2混合物,建立了精确测量CO2浓度的方法,测量了293K和0,4.1,8.1,13.3kPa下,CO2在6359.97cm-1的(30012)←(00001)R16e和6361.25cm-1的(30012)←(00001)R18e跃迁谱线,计算了R18e的谱线强度,通过比较35% CO2/N2混合物和其它CO2/N;2混合物的吸收面积,可以得到15%,10%,5%的CO2/N;2混合物的浓度。结果表明所建立的理论方法和实验结果能够较好地表征待测气体的浓度,测量不确定度与基于天平的称重法相当。     

Good enough tools for global warming policy making

We present a simple analysis of the global warming problem caused by the emissions of CO2 (a major greenhouse gas) into the atmosphere resulting from the burning of fossil fuels. We provide quantitative tools which enable policymakers and interested citizens to explore the following issues central to the global warming problem. (i) At what rate are we permitted to continue to emit CO2 after the global average atmospheric concentration has 'stabilized' at some chosen target level? The answer here provides the magnitude of the effort, measured by the necessary total reduction of today's global (annual) emissions rate to achieve stabilization. We shall see that stabilized emissions rates for all interesting stabilized concentration levels are much lower than the current emissions rate, but these small finite values are very important. (ii) Across how many years can we spread the total effort to reduce the annual CO2 emissions rate from its current high value to the above-mentioned low and stabilized target value? The answer here provides the time-scale of the total mitigation effort for any chosen atmospheric concentration target level. We confirm the common understanding that targets below a doubling of the pre-industrial concentration create great pressure to produce action immediately, while targets above double the pre-industrial level can tolerate longer periods of inaction. (iii) How much harder is the future mitigation effort, if we do not do our share of the job now? Is it a good idea to overshoot a stabilization target? The quantitative answers here provide the penalty of procrastination. For example, the mitigation task to avoid doubling the pre-industrial level is a problem that can be addressed gradually, over a period extending more than a century, if started immediately, but procrastination can turn the effort into a much more urgent task that extends over only a few decades. We also find that overshooting target levels is a bad idea. The quality of public discourse on this subject could be much enhanced if ball-park quantitative answers to these questions were more widely known.     

碳减排与绿色包装

在阐述气候变暖关系全人类生存环境的基础上,着重分析了包装的碳足迹、碳排放可能对包装形成新的绿色贸易壁垒,提出绿色包装是包装碳减排的主要途径及具体举措,同时分析了引进碳排放权交易对包装碳减排的重要意义。